This invention relates to pressure transducers in general and in particular to a tactile sensor from which information regarding the magnitude and pattern of pressure forces being sensed is transmitted by a signal medium for processing and analysis.
Pressure transducers having a flexible, pressure deformable reflector from which light radiation is reflected, is already well known as disclosed, for example, in U.S. Pat. No. 3,580,082 and in a technical paper authored by the applicants entitled "An Optical Tactile Sensor For Manipulators", published in 1984 in "Robotics & Computer-Integrated Manufacturing", Vol. 1, No. 1, pp. 65-71. In the foregoing type of transducer, a fiber bundle conducts light to and from a rigid base in which the optical fiber ends are embedded in spaced relation to each other. Light emerging from the fiber ends travels a short distance through a light transmitting medium to impinge on the flexible reflector and is reflected therefrom to reenter the fiber ends of the fiber bundle. The intensity of the reflected light reentering the fiber bundle depends on the variable reflection angles on the flexible reflector as a measure of its displacement under pressure loading. The light transmitting medium spacing the sensor base from the flexible reflector may be a transparent elastomer body through which the reflected light travels along paths determined by the reflection angles on the flexible reflector to vary the intensity of the reflected light as a function of pressure loading on the transducer.
The foregoing type of pressure transducer has not performed satisfactorily because of two major problems. First, the intensity of the reflected light output from the transducer is so small as to be overwhelmed by the glare produced during pick-up by a receiver, such as a video camera, as the light passes through a beam splitter. Second, the sensitivity of the transducer to pressure changes was found to be too low for detection as a computer input.
Accordingly, an important object of the present invention is to provide a pressure transducer through which passage of a signal medium is varied as a function of loading with improved sensitivity to changes in loading and to provide an output at a level that is more readily detectable.